Preceding national early warnings scores among in-hospital cardiac arrests and their impact on survival

ObjectivesIn-hospital cardiac arrests (IHCAs) are often preceded by abnormal vital signs. Preceding abnormal vital signs might lower the physiological reserve capacity and therefore decrease survival after an IHCA.AimTo assess the preceding national early warning score (NEWS) and its relation to survival after an IHCA.Material and methodsAll patients ≥ 18 years suffering an IHCA at Karolinska University Hospital between 1st January 2014 and 31st December 2015 were included. Data regarding the IHCA, patient characteristics, calculated NEWS and 30-day survival were obtained from electronic patient records. Parameters included in NEWSs were assessed up to 12 h before the IHCA. Differences in survival were assessed with adjusted logistic regression models and presented as Odds Ratios with 95% Confidence Intervals (OR, 95% CI) between patients with NEWSs of 0-4 points (low) versus those with at least 5 points (moderate) and 7 points (high). Adjustments included hospital site, sex, co-morbidities, first rhythm and location of the IHCA.ResultsIn all, 358 patients suffered an IHCA, of whom 109 (30%) survived at least 30 days and 296 (83%) had sufficient vital sign documentation to calculate NEWS before the IHCA. The 87 patients with a medium NEWS had a fourfold chance and those 78 with a high NEWS (22%) had an almost tenfold chance of dying after the IHCA compared to those with a low NEWS (Adjusted OR 4.43, 95% CI 1.81-10.83 and OR 9.88 95% C.I. 2.77-35.26, respectively).ConclusionThe NEWS can be a probable proxy for estimating physiological reserve capacity since high NEWS is associated to high change of death in case of an IHCA. This information can be used when discussing prognosis with patients and relatives. But even more importantly, it stresses the need for better preventive strategies in IHCAs.Strengthens and limitations with this study
- Strengths include the complete information about the outcome, i.e. 30-day survival or not due to Swedish Personal Identification Numbers and registries.
- Another strength is the collection of exposure data, NEWSs, was based on a strict a priori determined protocol, including only data documented in the medical record and therefore known to the staff before the IHCA.
- Limitations include the use of only documented vital signs, i.e. those taken but not documented, as well as the fact that information on interventions performed but not documented in the medical file are missing.
- A potential limitation is the lack of a control group with equally abnormal vital signs but no IHCA; such information would have answered the question how predictive the NEWS is for an IHCA but this is out of the scope of this study regardless.